Preheat the oven to 350°F.
Place potatoes in a large pot and cover with water. Bring to a boil, reduce heat, and cook for an additional 12-15 minutes (or until tender).
While potatoes are cooking, combine stuffing cubes, poultry seasoning, and sage in a large bowl. Stir in broth and pour into a greased 9x13 baking dish.
In another large bowl, combine the turkey, soup, garlic powder, and ¼ cup sour cream. Spoon over the stuffing mixture.
Drain potatoes and mash in a large bowl. Beat in the cream cheese, pepper, salt, and remaining sour cream, and spread over the turkey mixture.
Sprinkle with cheese and bake for 30-35 minutes. ENJOY!